Alternately expanding and contracting chambers are well known in the art, which devices employ various forms of rings or sliding surfaces to achieve sealing between adjacent parts. Commonly known is the piston-type combustion engine employing a closed cylinder, in which a piston, driven by a crankshaft and connecting rod, provides an alternately expanding and contracting chamber. Similarly, the well-known Wankel engine utilizes scraping edge seals between the rotating piston and chamber inner surfaces by which the gases are compressed and expanded. Obviously, such apparatus result in substantial friction between the contacting components thereby causing wear.
In an attempt to avoid these continually wearing seals or rings between moving parts, rotary engines have been proposed in U.S. Pat. Nos. 1,349,882 and 2,097,881. The earlier patent employs four elliptical piston between which the narrow spaces are sealed by spring-actuated rollers. In the latter patent, four elliptical rollers are in contact to define a combustion chamber therebetween. The problem with the aforesaid designs is their limitation because of the number of pistons or rollers as well as their shapes. Precise synchronization is required between the rotating and non-cylindrical rotors or pistons which is a significant disadvantage in apparatus design, as well as limiting the compression ratio of the chamber.